1. Field of the Invention
The present invention relates to an enhancer for biosynthesis of interferon and to a composition containing the enhancer.
2. Prior Art
Various compounds have been tested for activity as interferon inducers, and some have now been available under the trade names of Picibanil (a freeze-dried powder of Penicillin-treated Streptococcus pyrogenes), Krestin (a polysaccharide containing about 18-38% of protein and having an average molecular weight of about 100,000), and Maruyama Vaccine.
Additionally carcinostatics (Japanese Patent Publication No. 59-46493) and virocides (Japanese Patent Publication No. 62-34725) containing as effective ingredients dead bacterial mixtures of Pneumococcus, hemolytic Streptococcus, Staphylococcus, Neisseria catarrhalis, Tetracoccus, Pseudomonas aeruginosa, Klebsiella and Haemophilus influenzae have been known.
AIDS is a disease caused by human immuno-deficiency viruses (hereinafter HIV for short). Upon infection with such viruses, the helper T cell population of lymphocytes are destroyed resulting in cellular immuno-deficiency and eventually the patient succumbs opportunistic infections, Kaposi's sarcoma, etc., leading to high mortality rates.
When compared with human hepatitis virus infection, human leukemic retrovirus infection and other virus infections, the AIDS virus infections are much higher in incidence and in mortality-after-infection. To add to this, medicines now available for HIV infection are mainly inhibitor systems for the synthesis of nucleic acid, which have a grave demerit of attacking normal tissues rather than only producing a virocidal action. Thus, there is still a great demand for medicines which are safe to use and assure a high cure rate.
As reported in Japanese Patent Kokai Publication No. 52-115324, germanium polymers are effective for curing psychosis, neurosis, cacochymia, cardiopathy, anigopathy, digestive system dysfunctions, dermopathy, allergosis and renal and hepatic dysfunctions as well as various diseases in the realms of obstetrics and gynecology and pediatrics.
Additionally, Japanese Patent Kokai Publication No. 52-167222 and other publications teach that germanium polymers have an anti-DNA viral action upon influenza, Variola crystallina (herpes) and other DNA viruses.
However, nowhere in these publications is there any report on the action of organic germanium compounds as enhancers for the biosynthesis of interferon or the curing action thereof upon retroviral diseases, especially AIDS.
As is well known in the art, an organic germanium compound may be prepared as follows. Trichlorogermanium is allowed to react with acrylonitrile to obtain trichlorogermanium ethylnitrile. This is then hydrolyzed with an acid into trichlorogermanium ethyl carboxylate. Thereafter, this carboxylic acid is chlorinated with thionyl chloride into trichlorogermanium ethyl chloride which, upon exposed to water or aqueous ammonia, gives a bis-.beta.-ethyl carboxylic acid amide germanium sesquioxide.
The thus obtained organic germanium compound is not only different in structure and physical properties from the compound according to the present invention, it has the disadvantages of differing in action from lot to lot and being unclear as to how it acts and behaves.
It is understood that some organic germanium compounds have been reported to be effective as interferon inducers, but these are still not commercially available because it is not understood how they act and behave.
Investigated and developed to overcome the demerits of these known organic germanium compounds is such a germanium polymer compound as disclosed in Japanese Patent Kokai Publication No. 54-115324. This compound is essentially common in structure to the substance according to the present invention and produces a strong effect in relatively small dosages. It is thus said to be a useful compound that satisfies various requirements for medicines. However, problems with it are that it is not only apt to undergo chemical changes during storage over an extended period of time, it is hardly absorbable in living bodies in a stable manner when administrated thereto.
Consequently, the above germanium compound is now administrated in relatively large doses, while taking its decomposition into consideration. Because the germanium compound makes use of a rare element and with resource conservation in mind, however, there is an increased demand for investigations of various preparations and compositions, with which the germanium compound can directly produce its own strong action in small amounts.
In view of the state of the art as mentioned above, the present inventors have already discovered that the pharmacological action of the organic germanium compound according to the present invention can be enhanced by the addition of a carrier for pharmaceutical preparations such as sacchardies (e.g., lactose) or high-molecular compounds (e.g., proteins), and have thus accomplished preparing a composition usable as a medicine for external application for the purpose of preventing urtication, etc. due to immunodeficiency (Japanese Patent Kokai Publication No. 60-190714). As a result of later studies, the present inventors have found that the organic germanium compound per se according to the present invention has an effect on the enhancement of biosynthesis of interferon.